There is a great round up of the features and missing features of the Apple iPhone over on Gizmodo. Here is their list:

What it has:
• Built-in iPod with Video playback
• Intelligent predictive typing
• Multi-touch interface (fast)
• Great scratch resistant screen (easily cleaned with your sleeve)
• Tilt sensors that lock the screen when up to your face, but unlocks it when you lower it to type numbers
• Screen that's visible in direct sunlight
• Software upgrades over time
• Decent voice quality
• Call and song control from its headphones
• Viewing Word, Excel and PDF documents
• Free live traffic in Google Maps
• Turn by turn directions that simulate a GPS (need to tell the phone when you're turning)
• Dedicated volume control and mute switch
• Microsoft Exchange support if your IT staff enables a setting on the server
• Push email via Yahoo Mail
• Syncing via Outlook calendar and contacts through iTunes (works even on Vista with the latest Outlook)
• Ability to play with other applications while you talk
• Good battery life
• A "real" browser
• Yahoo, Gmail, AOL, EarthLink, and various other email support
• Visual voicemail (support for rewinding, fast forwarding like a song)
• YouTube support
• Decent 2-megapixel camera
• It's thin
• Lots of eye candy
• Conference call with up to 5 people
• Built-in speakers if you don't want to use headphones
• Quicktime support in Safari
• Activating the phone requires iTunes and internet access
• A speakerphone